Refrigeraton apparatus

ABSTRACT

Liquid lines (5LA, 5LB) and gas lines (5GA, 5GB) are connected to a main liquid line (4L) and a main gas line (4G) respectively so that a master outdoor unit (2A) and a slave outdoor unit (2B) are arranged in parallel with each other. On the gas line (5GB) extending from the slave outdoor unit (2B), a gas stop valve (V2) which is fully closed when the slave outdoor unit (2B) is deactivated during heating operation is disposed. On the liquid line (5LB) extending from the slave outdoor unit (2B), a liquid stop valve (V1) which is fully closed when the slave outdoor unit (2B) is deactivated during cooling operation and heating operation is disposed. Thus, compression of a liquid refrigerant and lack of a circulation amount of refrigerant are prevented.

This is a Divisional application of Ser. No. 08/307,701, filed Sep. 23,1994.

TECHNICAL FIELD

This invention relates to a refrigeration apparatus having a pluralityof thermal source units.

BACKGROUND ART

Conventionally, there has been known an air conditioner as arefrigeration apparatus in which a plurality of indoor units areconnected in parallel with one another through refrigerant piping withrespect to a single outdoor unit in order to form multi-type indoorunits, as disclosed in the Japanese Patent Application Laid Open GazetteNo. 4-208370. The outdoor unit has a compressor, a four-way selectorvalve, an outdoor heat exchanger, an outdoor motor-operated expansionvalve and a receiver. The indoor unit has an indoor motor-operatedexpansion valve and an indoor heat exchanger.

At a cooling operation, a refrigerant discharged from the compressor iscirculated, so as to be condensed at the outdoor heat exchanger, reducedin pressure at the indoor motor-operated expansion valve, evaporated atthe indoor heat exchanger and then returned to the compressor. During aheating operation, a refrigerant discharged from the compressor iscirculated, so as to be condensed at the indoor heat exchanger, reducedin pressure at the outdoor motor-operated expansion valve, evaporated atthe outdoor heat exchanger and then returned to the compressor.

Further, in the outdoor unit, the capacity of the compressor isregulated according to the load of the indoor unit.

Problems that the invention is to solve

In the above-mentioned air conditioner, since only a single outdoor unitis provided, it is required that may kinds of outdoor units havingdifferent capacities from one another are produced in correspondencewith the indoor load, i.e., the number of indoor units to be connected.In addition, when the indoor load does not accord with the capacity ofthe outdoor unit, the capacity of the outdoor unit is disadvantageouslyincreased in spite of a small indoor load.

To cope with the above problems, a plurality of outdoor units, forexample, two outdoor units, having different capacities from oneanother, may be combined with one another in order to form multi-typeoutdoor units.

In such a case, when the outdoor unit under cooling or heating operationand the outdoor unit in deactivation exist at the same time, therefrigerant must be prevented from being stored in the outdoor unit indeactivation in order that a fixed circulation amount of refrigerant isretained. That is, it is necessary to prevent lack of a circulationamount of refrigerant.

Further, when one of the outdoor units is deactivated during heatingoperation, a large amount of gas refrigerant can be condensed in theoutdoor unit or the refrigerant piping. Therefore, it is required toprevent the compressor from compressing a liquid refrigerant uponreactivation of the outdoor unit.

Furthermore, when the air conditioner has a plurality of outdoor units,the refrigerant piping extending from the outdoor units is connected totwo main pipes and the main pipes conducted on the indoor side. However,in case that the piping arrangement is made at a free hand at theinstallation, an angle of tilt of piping required for backing oil cannotbe secured or a part of piping to be horizontally arranged may beinclined. This disadvantageously prevents high-reliable airconditioning.

In view of the foregoing problems, this invention has been made. Thepresent invention has its object of preventing the compression of aliquid refrigerant and the lack of a circulation amount of refrigerantowing to the storage of the refrigerant and the like and securing anaccurate installation of the refrigerant piping.

DISCLOSURE OF INVENTION

To attain the foregoing object, a refrigeration apparatus of the presentinvention has a closing mechanism for allowing and preventing a flow ofrefrigerant, and/or has ejecting means for ejecting a refrigerant orrecovering means for recovering a refrigerant, and/or has a constructionin which a connecting part of a plurality of thermal source units isunitized.

Construction

In detail, a refrigeration apparatus of this invention comprises aplurality of thermal source units (2A, 2B) which each have a compressor(21) and a thermal-source-side heat exchanger (24) connected at an endthereof to the discharge side of the compressor (21), and in whichliquid lines (5LA, 5LB) are connected to the other ends of thethermal-source-side heat exchangers (24) respectively and gas lines(5GA, 5GB) are connected to the inlet sides of the compressors (21)respectively. Further, in the refrigeration apparatus, there is provideda connecting circuit part (11) for connecting outer ends of the liquidlines (5LA, 5LB) and outer ends of the gas lines (5GA, 5GB) to a mainliquid line (4L) and a main gas line (4G) respectively so that thethermal source units (2A, 2B) are arranged in parallel with one another.Furthermore, the refrigeration apparatus has a plurality of use units(3A, 3B) which each have a user-side expansion mechanism (33) and auser-side heat exchanger (32) and which are connected to the main liquidline (4L) and the main gas line (4G) so as to be arranged in parallelwith one another.

In addition, on the liquid line (5LB) of at least one thermal sourceunit (2B) between the plural thermal source units (2A, 2B), there isdisposed a liquid-line closing mechanism (V1) which is fully closed whenthe thermal source unit (2B) is deactivated during cooling operation.

In a refrigeration apparatus of the present invention, a receiver (12)for connecting each of the liquid lines (5LA, 5LB) to the main liquidline (4L) is disposed at a connecting part between the liquid lines(5LA, 5LB) and the main liquid line (4L).

As shown in FIG. 1, a refrigeration apparatus of the present inventioncomprises: a master thermal source unit (2A) which has a compressor(21), a thermal-source-side heat exchanger (24) connected at an endthereof to the discharge side and the inlet side of the compressor (21)so as to be switchable between the two sides of the compressor (21) andat the other end to a liquid line (5LA), and a thermal-source-sideexpansion mechanism (25) disposed on the liquid line (5LA), and in whicha gas line (5GA) is connected to the discharge side and the inlet sideof the compressor (21) so as to be switchable between the two sides ofthe compressor (21); a slave thermal source unit (2B) which has acompressor (21), a thermal-source-side heat exchanger (24) connected atan end thereof to the discharge side and the inlet side of thecompressor (21) so as to be switchable between the two sides of thecompressor (21) and at the other end to a liquid line (5LB), and athermal-source-side expansion mechanism (25) disposed on the liquid line(5LB), and in which a gas line (5GB) is connected to the discharge sideand inlet side of the compressor (21) so as to be switchable between thetwo sides of the compressor (21). Further, in the refrigerationapparatus, there is provided a connecting circuit part (11) forconnecting outer ends of the liquid lines (5LA, 5LB) and outer ends ofthe gas lines (5GA, 5GB) to a main liquid line (4L) and a main gas line(4G) respectively so that the thermal source units (2A, 2B) are arrangedin parallel with each other. Furthermore, the refrigeration apparatushas a plurality of user units (3A, 3B) which each have a user-side heatexchanger (32) and which are connected to the main liquid line (4L) andmain gas line (4G) so as to be arranged in parallel with one another.

In addition, on the liquid line (5LB) extending toward the slave thermalsource unit (2B), there is disposed a liquid-line closing mechanism (V1)which fully closed when the slave thermal source unit (2B) isdeactivated during refrigerating operation. On the gas line (5GB)extending toward the slave thermal source unit (2B), there is provided agas-line closing mechanism (V2) which is fully closed when the slavethermal source unit (2B) is deactivated during heating operation.

In a refrigeration apparatus of the present invention, a receiver (12)for connecting each of the liquid lines (5LA, 5LB) to the main liquidline (4L) is disposed at a connecting part between the liquid lines(5LA, 5LB) and the main liquid line (4L).

In a refrigeration apparatus of the present invention, a bypass line(29) which bypasses the compressor (21) of the slave thermal source unit(2B) is connected to the discharge and inlet sides of the compressor(21), and a bypass closing mechanism (V3) is disposed on the bypass line(29). Further, there is disposed refrigerant ejecting means (61) forejecting a liquid refrigerant remaining in the slave thermal source unit(2B) in such a manner as to open the bypass closing mechanism (V3) andthe thermal-source-side expansion mechanism (25) each included in theslave thermal source unit (2B) in deactivation, the liquid-line closingmechanism (V1) and the gas-line closing mechanism (V2) for a set timejust after the slave thermal source unit (2B) is deactivated duringheating operation.

In a refrigeration apparatus of the present invention, there is disposedin each of the user units (3A, 3B) a user-side expansion mechanism (33)which is located between the main liquid line (4L) and the user-sideheat exchanger (32). Further, there are provided: refrigerant-amountdetecting means (62) for detecting lack of a circulation amount ofrefrigerant; and refrigerant recovering means (63) for recovering arefrigerant from the slave thermal source unit (2B) in deactivation whenthe slave thermal source unit (2B) is deactivated during heatingoperation and the refrigerant-amount detecting means (62) detects thelack of a circulation amount of refrigerant, in such a manner as to openthe thermal-source-side expansion mechanism (25) of the slave thermalsource unit (2B) in deactivation and the liquid-line closing mechanism(V1) and throttle the user-side expansion mechanism (33) so as to reducea pressure of a liquid refrigerant to a saturation pressure according toan open-air temperature.

As shown in FIG. 2, a refrigeration apparatus of the present inventioncomprises: a master thermal source unit (2A) having a compressor (21), athermal-source-side heat exchanger (24) connected at an end thereof tothe discharge side and the inlet side of the compressor (21) so as to beswitchable between the two sides of the compressor (21) and at the otherend to a liquid line (5LA) and a thermal-source-side expansion mechanism(25) which is disposed on the liquid line (5LA) and capable ofregulating an opening thereof, in which a gas line (5GA) is connected tothe discharge side and the inlet side of the compressor (21) so as to beswitchable between the two sides of the compressor (21); a slave thermalsource unit (2B) having a compressor (21), a thermal-source-side heatexchanger (24) connected at an end thereof to the discharge side and theinlet side of the compressor (21) so as to be switchable between the twosides of the compressor (21) and at the other end to a liquid line(5LB), and a thermal-source-side expansion mechanism (25) which isdisposed on the liquid line (5LB) and capable of regulating an openingthereof, in which a gas line (5GB) is connected to the discharge sideand the inlet side of the compressor (21) so as to be switchable betweenthe two sides of the compressor (21); a connecting circuit part (11) forconnecting outer ends of the liquid lines (5LA, 5LB) and outer ends ofthe gas lines (5GA, 5GB) to a main liquid line (4L) and a main gas line(4G) respectively so that the thermal source units (2A, 2B) are arrangedin parallel with each other; and a plurality of user units (3A, 3B)which each have a user-side heat exchanger (32) and which are connectedto the main liquid line (4L) and the main gas line (4G) so as to bearranged in parallel with one another.

Further, at a connecting part located between the liquid lines (5LA,5LB) and the main liquid line (4L) a receiver (12) which connects eachof the liquid lines (5LA, 5LB) to the main liquid line (4L) is disposed.In addition, on the gas line (5GB) extending toward the slave thermalsource unit (2B), there is provided a gas-line closing mechanism (V2)which is fully closed when the slave thermal source unit (2B) isdeactivated during heating operation. Furthermore, there is providedfull-closure control means (6) for controlling the thermal-source-sideexpansion mechanism (25) of the slave thermal source unit (2B) indeactivation to be fully closed when the slave thermal source unit (2B)is deactivated during refrigerating operation.

In a refrigeration apparatus of the present invention, a bypass line(29) which bypasses the compressor (21) of the slave thermal source unit(2B) is connected to the discharge and inlet sides of the compressor(21), and a bypass closing mechanism (V3) is provided on the bypass line(29). Further, there is disposed refrigerant ejecting means (61) forejecting a liquid refrigerant remaining in the slave thermal source unit(2B) in such a manner as to open the bypass closing mechanism (V3) andthe thermal-source-side expansion mechanism (25) each included in theslave thermal source unit (2B) in deactivation, and the gas closingmechanism (V2) for a set time just after the slave thermal source unit(2B) is deactivated during heating operation.

In a refrigeration apparatus of the present invention, there is providedin each of the user units (3A, 3B) a user-side expansion mechanism (33)located between the main liquid line (4L) and the user-side heatexchanger (32). Further, the refrigeration apparatus hasrefrigerant-amount detecting means (62) for detecting lack of acirculation amount of refrigerant, and refrigerant recovering means (63)for recovering a refrigerant from the slave thermal source unit (2B) indeactivation when the slave thermal source unit (2B) is deactivatedduring heating operation and the refrigerant-amount detecting means (62)detects the lack of a circulation amount of refrigerant, in such amanner as to open the thermal-source-side expansion mechanism (25) ofthe slave thermal source unit (2B) in deactivation and throttle theuser-side expansion mechanism (33) so as to reduce a pressure of theliquid refrigerant to a saturation pressure according to an open-airtemperature.

As shown in FIG. 7, a refrigerant recovering line (8) through which arefrigerant flows from the slave thermal source unit (2B) to the masterthermal source unit (2A) is disposed between a gas-refrigerant pipe (26)extending from the thermal-source-side heat exchanger (24) of the masterthermal source unit (2A) and the gas line (5GB) extending from the slavethermal source unit (2B).

As shown in FIG. 9, a refrigeration apparatus of the present inventionhas a connecting circuit part (11) for connecting each of outer ends ofliquid lines (5LA, 5LB) of master and slave thermal source units (2A,2B) to a main liquid line (4L) and connecting an outer end of the gasline (5GA) of the master thermal source unit (2A) to a main gas line(4G), instead of the connecting circuit part (11) and the gas closingmechanism (V2) of claim 3. Further, in the refrigeration apparatus,there is disposed a branch line (5a) which is connected at an endthereof to a gas-refrigerant pipe (26) extending from thethermal-source-side heat exchanger (24) of the master thermal sourceunit (2A). In addition, in the connecting circuit part (11), there isdisposed a constant-pressure circuit (9): which has a normallyhigh-pressure passage (91) held normally in a state of high pressure anda normally low-pressure passage (92) held normally in a state of lowpressure; and in which the normally high-pressure passage (91) and thenormally low-pressure passage (92) are each connected to the main gasline (4G) and the branch line (5a). In the constant-pressure circuit(9), the gas line (5GB) of the slave thermal source unit (2B) isconnected to the normally high-pressure passage (91), in order that arefrigerant flows from the gas line (5GB) toward normally high-pressurepassage (91), and the gas line (5GB) of the slave thermal source unit(2B) is connected to the normally low-pressure passage (92) in orderthat a refrigerant flows from the normally low-pressure passage (92)toward the gas line (5GB).

In a refrigeration apparatus of the present invention, a receiver (12)for connecting each of the liquid lines (5LA, 5LB) to the main liquidline (4L) is disposed at a connecting part between the liquid lines(5LA, 5LB) and the main liquid line (4L).

As shown in FIG. 10, in a refrigeration apparatus of the presentinvention, there are provided a connecting circuit part (11), a branchline (5a) and a constant-pressure circuit (9) as are in claim 11,instead of the connecting circuit part (11) and the gas-line closingmechanism (V2).

In a refrigeration apparatus of the present invention, a refrigerantrecovering passage (8a) through which a refrigerant flows from the gasline (5GB) of the slave thermal source unit (2B) toward the normallylow-pressure passage (92) of the constant-pressure circuit (9) isconnected between the normally low-pressure passage (92) and the gasline (5GB).

As shown in FIG. 11, in a refrigeration apparatus of the presentinvention, there is provided a connecting gas line (10) which isconnected at respective ends thereof to the respective gas-refrigerantpipes (26) of the thermal-source-side heat exchangers (24) of thethermal source units (2A, 2B) and which has a closing mechanism (V19)for preventing a refrigerant from flowing, when at least one thermalsource unit (2B) is deactivated during cooling operation, into thethermal source unit (2B) in deactivation.

In a refrigeration apparatus of the present invention, the connectingcircuit part (11) is formed in a single unit.

OPERATION

Under the above constructions, in the refrigeration apparatushigh-pressure gas refrigerants discharged from the compressors (21) ofthe thermal source units (2A, 2B) are first condensed at thethermal-source-side heat exchangers (24) to turn liquid refrigerants.The two flows of the liquid refrigerants meet at the main liquid line(4L) of the connecting circuit part (11). In particular, in case of therefrigeration apparatus of claim 2, the liquid refrigerants meet at thereceiver (12). Then, in each of the user units (3A, 3B), the liquidrefrigerant is reduced in pressure at the user-side expansion mechanism(33) and evaporated at the user-side heat exchanger (32) to turn a gasrefrigerant having low pressure. The gas refrigerant is distributed atthe connecting circuit part (11) to the gas lines(5GA, 5GB) and thenreturned to the compressors (21) of the thermal source units (2A, 2B). Acooling operation is made by repeating the above circulating process.

Further, when at least one thermal source unit (2B) is deactivatedduring cooling operation, the liquid-line closing mechanism (V1) isclosed to prevent the liquid refrigerant from being stored in thethermal source unit (2B).

In the refrigeration apparatus of the present invention, at its coolingoperation, high-pressure gas refrigerants discharged from thecompressors (21) of the thermal source units (2A,2B) are first condensedat the thermal-source-side that heat exchangers (24) to turn liquidrefrigerants. The two flows of the liquid refrigerants meet at the mainliquid line (4L) of the connecting circuit part (11). In particular, incases of the refrigeration apparatus of claims 4 and 7, the liquidrefrigerants meet at the receiver (12). Then, in each of the user units(3A,3B), the liquid refrigerant is reduced in pressure at the user-sideexpansion mechanism (33) or the like and evaporated at the user-sideheat exchanger (32) to turn a gas refrigerant having low pressure. Thegas refrigerant is distributed at the connecting circuit part (11) tothe gas lines (5GA,5GB) and then returned to the compressors (21) of thethermal source units (2A,2B). The cooling operation is made by repeatingthe above circulating process.

At a heating operation, high-pressure gas refrigerants discharged fromthe compressors (21) of the thermal source units (2A,2B) flow into theconnecting circuit part (11) and meet at the main gas line (4G). Then,the collected gas refrigerant flows into the user units (3A,3B). The gasrefrigerant is condensed at each of the user-side heat exchangers (32)to turn a liquid refrigerant. The liquid refrigerant flows through themain liquid line (4L) and then is distributed at the connecting circuitpart (11) to the liquid lines (5LA,5LB) running to the thermal sourceunits (2A,2B). In particular, the refrigerant is distributed at thereceiver (12). Then, in the thermal source units (2A,2B), thedistributed liquid refrigerants are each reduced in pressure at thethermal-source-side expansion mechanism (25) and evaporated at thethermal-source-side heat exchanger (24) to turn a gas refrigerant havinglow pressure. Then, the gas refrigerants are returned to the compressors(21) of the thermal source units (2A,2B). The heating operation is madeby repeating the above circulating process. When the slave thermalsource unit (2B) is deactivated during heating operation, the gas-lineclosing mechanism (V2) is closed, so that the liquid refrigerant isprevented from being stored in the slave thermal source unit (2B) indeactivation and a circulation amount of refrigerant is prevented frombeing lacked between the master thermal source unit (2A) and the userunits (3A,3B).

Further, when the slave thermal source unit (2B) is deactivated duringcooling operation and heating operation, the liquid-line closingmechanism (V1) or the thermal-source-side expansion mechanism (25) isclosed, so that the liquid refrigerant is prevented from being stored inthe slave thermal source unit (2B) in deactivation and a circulationamount of refrigerant is prevented from being lacked between the masterthermal source unit (2A) and the user units (3A,3B).

In the refrigeration apparatus of the present invention, just after theslave thermal source unit (2B) is deactivated during heating operation,the refrigerant ejecting means (61) opens the bypass closing mechanism(V3), the thermal-source-side expansion mechanism (25) of the slavethermal source unit (2B), the liquid-line closing mechanism (V1) and thegas-line closing mechanism (V2) for a set time. Just after the slavethermal source unit (2B) is deactivated during heating operation, therefrigerant ejecting means (61) opens the bypass closing mechanism (V3),the thermal-source-side expansion mechanism (25) of the slave thermalsource unit (2B) and the gas-line closing mechanism (V2) for a set time.Consequently, the high-pressure gas refrigerant in the master thermalsource unit (2A) flows into the liquid line (5LB) via the gas line (5GB)of the slave thermal source unit (2B), so that the liquid refrigerantremaining in the slave thermal source unit in deactivation is ejectedinto the main liquid line (4L) or the like, thus preventing lack of acirculating amount of refrigerant.

In detail, when the refrigerant flows through the main gas line (4G) orthe like, the pressure of the refrigerant is reduced due to a pressureloss. In the user units (3A,3B) under heating operation, the differencebetween the pressure losses of the user units (3A,3B) resulting from thedifference between the piping lengths thereof is compensated. Forexample, the difference between the pressure losses is compensated by amotor-operated expansion valve as the user-side expansion mechanism(33). As a result of this, the pressure of the refrigerant in the mainliquid line (4L) becomes lower than the pressure of the refrigerantwhich is discharged from the compressor (21), so that the liquidrefrigerant remaining in the slave thermal source unit (2B) is ejectedinto the main liquid line (4L) or the like.

In the refrigeration apparatus, when the slave thermal source unit (2B)is deactivated during heating operation and the refrigerant-amountdetecting means (62) detects lack of a circulating amount ofrefrigerant, the refrigerant recovering means (63) opens thethermal-source-side expansion mechanism (25) and the liquid-line closingmechanism (V1) and throttles the user-side expansion mechanism (33),thereby reducing the pressure of the liquid refrigerant to a saturationpressure according to an open-air temperature. In the refrigeratingapparatus, when the slave thermal source unit (2B) is deactivated duringheating operation and the refrigerant-amount detecting means (62)detects lack of a circulating amount of refrigerant, the refrigerantrecovering means (63) opens the thermal-source-side expansion mechanism(25) and throttles the user-side expansion mechanism (33), therebyreducing the pressure of the liquid refrigerant to a saturation pressureaccording to an open-air temperature. Consequently, the liquidrefrigerant remaining in the slave thermal source unit (2B) indeactivation is evaporated so that the evaporated refrigerant isreturned to the master thermal source unit (2A).

When the slave thermal source unit (2B) is deactivated during heatingoperation, the refrigerant recovering line (8) establishescommunications between the gas line (5GB) connecting to the slavethermal source unit (2B) and a low-pressure gas side of the masterthermal source unit (2A), so that the refrigerant remaining in the slavethermal source unit (2B) in deactivation is returned to the masterthermal source unit (2A).

A gas refrigerant flowing into the slave thermal source unit (2B) and agas refrigerant discharged from the slave thermal source unit (2B) flowthrough the normally high-pressure passage (91) and the normallylow-pressure passage (92) each forming the constant-pressure circuit (9)when flowing between the gas line (5GB) and the main gas line (4G).Accordingly, the liquid refrigerant is prevented from being stored inthe slave thermal source unit (2B) without the gas-line closingmechanism (V2).

Further, the receiver (12) collects and distributes the liquidrefrigerant.

When the slave thermal source unit (2B) is deactivated during heatingoperation, the refrigerant recovering passage (8a) normally establishescommunications between the gas line (5GB) connecting to the slavethermal source unit (2B) and a low-pressure gas side of the masterthermal source unit (2A) through the constant-pressure circuit (9), sothat the refrigerant remaining in the slave thermal source unit (2B) indeactivation is returned to the master thermal source unit (2A).

The gas-refrigerant pipes (26) of the thermal-source side heatexchangers (24) of the thermal source units (2A,2B) are communicatedwith each other through the connecting gas line (10). Accordingly,circulation amounts of refrigerants which flow through the respectivethermal-source-side heat exchangers (24) are approximately equal to eachother, thereby increasing a coefficient of performance (COP) of therefrigeration apparatus.

EFFECTS

According to the refrigeration apparatus of the present invention, sincethe liquid line (5LB) of at last one thermal source unit (2B) isprovided with the liquid-line closing mechanism (V1) which is fullyclosed when the thermal source unit (2B) is deactivated during coolingoperation, a liquid refrigerant is prevented from being stored in thethermal source unit (2B) in deactivation. This prevents lack of acirculation amount of refrigerant between another thermal source unit(2A) and user units (3A,3B).

As a result of this, a plurality of thermal source units (2A,2B) can becombined. Further, since a plurality of thermal source units (2A,2B)having different capacities from one another can be produced andcombined, this enables a few kinds of thermal source units (2A,2B) tocope with many kinds of loads.

Since provision of a single receiver (12) can dispense with respectivereceivers of the thermal source units (2A,2B), this reduces the numberof elements. Further, since distribution of a liquid refrigerant issecurely carried out, an unbalanced flow of refrigerant can be securelyprevented even when a flash of gas flows into the main liquid line (4L)or the like.

The gas-line closing mechanism (V2) and the liquid-line closingmechanism (V1) are disposed on the gas line (5GB) and the liquid line(5LB) which connect to the slave thermal source unit (2B) respectively,the liquid-line closing mechanism (V1) is closed when the slave thermalsource unit (2B) is deactivated during cooling operation and heatingoperation, and the gas-line closing mechanism (V2) is closed when theslave thermal source unit (2B) is deactivated during heating operation.Accordingly, a liquid refrigerant can be prevented from being stored inthe slave thermal source unit (2B) in deactivation, for example, theliquid refrigerant can be prevented from being stored in a receiver orthe like. In detail, because the pressure of the liquid refrigerant atthe operation time is higher than a saturation pressure according to anopen-air temperature, the liquid refrigerant may be stored in thereceiver and the like. In this refrigeration apparatus, the storage ofthe liquid refrigerant can be prevented.

Further, according to this refrigeration apparatus, lack of acirculation amount of refrigerant between the master thermal source unit(2A) and the user units (3A,3B) can be prevented, and it is preventedthat the liquid refrigerant remaining in the slave thermal source unit(2B) is compressed by the compressor (21) at a reactivation of the slavethermal source unit (2B).

As a result of this, a plurality of thermal source units (2A,2B) can becombined. In addition, since a plurality of thermal source units (2A,2B)having different capacities from one another can be produced andcombined, this enables a few kinds of thermal source units (2A,2B) tocope with many kinds of loads.

Since provision of a single receiver (12) can dispense with respectivereceivers of the thermal source units (2A,2B), this reduces the numberof elements. Further, since distribution of a liquid refrigerant issecurely carried out, an unbalanced flow of refrigerant can be securelyprevented even when a flash of gas flows into the main liquid line (4L)or the like.

Just after the slave thermal source unit (2B) is deactivated duringheating operation, the refrigerant ejecting means (61) operates so thata high-pressure gas refrigerant flows from the master thermal sourceunit (2A) into the liquid line (5LB) via the gas line (5GB) and theslave thermal source unit (2B). Accordingly, the liquid refrigerantremaining in the slave thermal source unit (2B) in deactivation isejected into the main liquid line (41) or the like, thereby securelypreventing lack of a circulation amount of refrigerant.

When the refrigerant-amount detecting means (62) detects lack of acirculation amount of refrigerant, the refrigerant recovering means (63)throttles the user-side expansion mechanism (33) to reduce a pressure ofa liquid refrigerant to a saturation pressure according to an open-airtemperature. As a result of this, the liquid refrigerant remaining inthe slave thermal source unit (2B) in deactivation is evaporated andreturned to the master thermal source unit (2A). Accordingly, the lackof a circulation amount of refrigerant can be securely prevented at anytime.

Since the thermal-source-side expansion mechanism (25) is fully closedwhen the slave thermal source unit (2B) is deactivated during coolingoperation and heating operation, storage of a liquid refrigerant intothe slave thermal source unit (2B) can be prevented as in the case ofclaim 3. Further, since a liquid-line closing mechanism (V1) can bedispensed with, the number of elements can be reduced.

When the slave thermal source unit (2B) is deactivated during heatingoperation, the refrigerant recovering line (8) establishescommunications between the gas line (5GB) connecting to the slavethermal source unit (2B) and a low-pressure gas side of the masterthermal source unit (2A). Accordingly, a refrigerant remaining in theslave thermal source unit (2B) in deactivation can be returned to themaster thermal source unit (2A). In addition, since the refrigerantejecting means (61) and the refrigerant recovering means (63) can bedispensed with, the construction of the refrigeration apparatus can besimplified.

Since there is provided the constant-pressure circuit (9) through whichgas refrigerants flowing into and from the slave thermal source unit(2B) pass, the high-pressure gas refrigerant does not flow into theslave thermal source unit (2B) when the slave thermal source unit (2B)is deactivated during refrigerating operation. Accordingly, storage of aliquid refrigerant into the slave thermal source unit (2B) can beprevented. In addition, since the gas-line closing mechanism (V2) can bedispensed with, the construction of the refrigeration apparatus can besimplified.

When the slave thermal source unit (2B) is deactivated during heatingoperation, the constant-pressure circuit (9) and the refrigerantrecovering passage (8a) establishes communications between the gas line(5GB) connecting to the slave thermal source unit (2B) and alow-pressure gas side of the master thermal source unit (2A).Accordingly, a refrigerant remaining in the slave thermal source unit(2B) in deactivation can be returned to the master thermal source unit(2A). In addition, since the refrigerant ejecting means (61) and therefrigerant recovering means (63) can be dispensed with, theconstruction of the refrigeration apparatus can be simplified.

Since the gas-refrigerant pipes (26) of the thermal-source-side heatexchangers (24) of the thermal source units (2A,2B) are communicatedwith each other, circulation amounts of refrigerants which flow throughthe respective thermal-source-side heat exchangers (24) can beapproximately equal to each other, thereby increasing a coefficient ofperformance (COP) of the refrigeration apparatus. In addition, betweenthe thermal source units (2A,2B), a high-pressure sensor for detecting ahigh pressure at a cooling operation and a low-pressure sensor fordetecting a low pressure at a heating operation can be shared. Thisreduces the number of elements.

Further, when the slave thermal source unit (2B) is deactivated duringheating operation, a refrigerant remaining in the slaver thermal sourceunit (2B) in deactivation can be securely returned to the master thermalsource unit (2A).

Since the connecting circuit part (11) between the thermal source units(2A,2B) and the user units (3A,3B) is unitized, an angle of tilt ofpiping required for backing oil can be secured and a part of piping tobe horizontally arranged can be held in a horizontal position. Thisenables high-reliable air conditioning. In addition, since the number ofpipes can be reduced when a plurality of thermal source units (2A,2B)are installed, this reduces the number of steps at a pip arrangement,thereby simplifying the pipe arrangement.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a refrigerant circuit diagram of an air conditioner showingExample 1 of a refrigeration apparatus of the present invention.

FIG. 2 is a refrigerant circuit diagram of an air conditioner showingExample 2 of a refrigeration apparatus of the present invention.

FIG. 3 is a refrigerant circuit diagram of an air conditioner showing amodification of the Example 2.

FIG. 4 is a refrigerant circuit diagram of an air conditioner showinganother modification of the Example 2.

FIG. 5 is a sectional view showing than an external-equalizing-typereversible valve is opened.

FIG. 6 is a sectional view showing that the external-equalizing-typereversible valve is closed.

FIG. 7 is a refrigerant circuit diagram of an air conditioner showingExample 3 of a refrigeration apparatus of the present invention.

FIG. 8 is a refrigerant circuit diagram of an air conditioner showing amodification of the Example 3.

FIG. 9 is a refrigerant circuit diagram of an air conditioner showingExample 4 of a refrigeration apparatus of the present invention.

FIG. 10 is a refrigerant circuit diagram of an air conditioner showing amodification of the Example 4.

FIG. 11 is a refrigerant circuit diagram of an air conditioner showingExample 5 of a refrigeration apparatus of the present invention.

FIG. 12 is a refrigerant circuit diagram of an air conditioner showing amodification of the Example 5.

BEST MODE FOR CARRYING OUT THE INVENTION

Detailed description is made below about examples of the presentinvention, with reference to the drawings.

EXAMPLE 1

FIG. 1 shows an example of a refrigeration apparatus of the presentinvention. Reference numeral (1) indicates an air conditioner as arefrigeration apparatus. In the air conditioner (1), two outdoor units(2A,2B) are connected to a main liquid line (4L) and a main gas line(4G) so as to be arranged in parallel with each other, and two indoorunits (3A,3B) are connected to the main liquid line (4L) and the maingas line (4G) so as to be arranged in parallel with each other.

Each of the outdoor units (2A,2B) serves as a thermal source unit havinga compressor (21), a four-way selector valve (22), an outdoor heatexchanger (24) as a thermal-source-side heat exchanger which is in theproximity of an outdoor fan (23), and an outdoor motor-operatedexpansion valve (25) as a thermal-source-side expansion mechanism. Anend of the outdoor heat exchanger (24) in which gas flows is connectedto a gas-refrigerant pipe (26) and another end thereof in which liquidflows is connected to a liquid line (5LA,5LB).

The gas-refrigerant pipe (26) is connected to a discharge side of aninlet side of the compressor (21) via the four-way valve (22) whichswitchably selects the discharge and inlet sides of the compressor (21).The liquid line (5LA,5LB) extending from the outdoor heat exchanger (24)is connected to the main liquid line (4L) via the outdoor motor-operatedexpansion valve (25) and a receiver (27) for storing a liquidrefrigerant in order.

Further, the compressor (21) is connected to a gas line (5GA,5GB) viathe refrigerant pipe (26). The gas line (5GA,5GB) is connected to thedischarge side and the inlet side of the compressor (21) via thefour-way valve (22) which switchably selects the discharge and inletsides of the compressor (21), and also connected to the main gas line(4G). An accumulator (28) is provided between the inlet side of thepressor (21) and the four-way valve (22) in the middle of thegas-refrigerant pipe (26).

Each of the indoor units (3A,3B) serves as a user unit having an indoorheat exchanger (32) as a user-side heat exchanger which is in theproximity of an indoor fan (31), and an indoor motor-operated expansionvalve (33) as a user-side expansion mechanism. The indoor heat exchanger(32) is connected to the main liquid line (4L) via an indoor liquid pipe(34) and connected to the main gas line (4G) via an indoor gas pipe(35). The indoor motor-operated expansion valve (33) is disposed in theindoor liquid pipe (34).

The two outdoor units (2A,2B) is one of the features of the presentinvention, and so composed that a single master outdoor unit (2A) and asingle slave outdoor unit (2B) are connected in parallel with eachother. The capacity of each outdoor unit (2A,2B) is set according to anindoor load, i.e., the number of indoor units (3A,3B). The compressor(21) of the master outdoor unit (2A) is composed so that the capacitythereof is set in multi-steps by an inverter circuit, while thecompressor (21) of the slave outdoor unit (2B) is composed so that thecapacity thereof is set switchably among 100%, 50%, and 0% by unloadingcontrol.

Furthermore, various kinds of sensors are disposed in the master outdoorunit (2A) and the indoor units (3A,3B).

In the master outdoor unit (2A), a discharge-gas temperature sensor(Th1) for detecting a temperature of a gas refrigerant discharged fromthe compressor (21) is disposed at a part of the gas-refrigerant pipe(26) which is located on the discharge side of the compressor (21), aninlet-gas temperature sensor (Th2) for detecting a temperature of a gasrefrigerant to be sucked into the compressor (21) is disposed at a partof the refrigerant pipe (26) which is located on the inlet side of thecompressor (21), an outdoor-liquid temperature sensor (Th3) fordetecting a temperature of a liquid refrigerant on the outdoor heatexchanger's (24) side is disposed on the liquid line (5LA), and anopen-air temperature sensor (Th4) for detecting a temperature of openair is disposed in the vicinity of the outdoor heat exchanger (24).Further, a high-pressure sensor (HPS) for detecting a pressure of a gasrefrigerant discharged from the compressor (21) is disposed at a portionof the gas-refrigerant pipe (26) which is located on the discharge sideof the compressor (21), and a low-pressure sensor (LPS) for detecting apressure of a gas refrigerant to be sucked into the compressor (21) isdisposed at a portion of the gas-refrigerant pipe (26) which is locatedon the inlet side of the compressor (21).

In each of the indoor units (3A,3B), an indoor-liquid temperature sensor(Th5) for detecting a temperature of a liquid refrigerant on the indoorheat exchanger's (32) side is disposed in the indoor liquid pipe (34),an indoor-gas temperature sensor (Th6) for detecting a temperature of agas refrigerant on the indoor heat exchanger's (32) side is disposed inthe indoor gas pipe (35), and a room temperature sensor (Th7) fordetecting a room temperature is disposed in the vicinity of the indoorfan (31).

Detection signals from the above sensors (Th1-Th7, HPS, LPS) areinputted into a controller (6), and based on the detection signals, thecontroller (6) controls openings of the motor-operated expansion valve(25,33) and the capacity of the compressor (21) and the like.

The air conditioner (1) has a piping unit (11) as a connecting circuitpart. The piping unit (11) is one of features of the present invention,and connects the liquid lines (5LA,5LB) and the gas lines (5GA,5GB) onthe indoor unit's (2A,2B) side to the main liquid line (4L) and the maingas line (4G), respectively.

In detail, each of the liquid lines (5LA,5LB) is composed of a liquidpipe (51,52) extending outward from the outdoor unit (2A,2B) and aliquid passage (53,54) connecting to an outer end of the liquid pipe(51,52). The liquid pipe (51,52) is connected in an inner end thereof tothe outdoor heat exchanger (24). The outdoor motor-operated expansionvalve (25) and the receiver (27) are disposed in the liquid pipe(51,52).

Each of the gas lines (5GA,5GB) is composed of a gas pipe (55,56)extending outward from the outdoor unit (2A,2B) and a gas passage(57,58) connecting to an outer end of the gas pipe (55,56). The gas pipe(55,56) is connected to the compressor (21) via the four-way selectorvalve (22).

The main liquid line (4L) is composed of a main liquid pipe (41)extending on the indoor unit's (3A,3B) side, and a main liquid passage(42) connecting to an end of the main liquid pipe (41) and the liquidpassages (53,54) on the outdoor unit's (2A,2B) side. The main liquidpipe (41) is connected at the other end thereof to the indoor liquidpipes (34) of the indoor units (3A,3B).

Each of the main gas lines (4G) is composed of a main gas pipe (43)extending on the indoor unit's (3A,3B) side, and a main gas passage (44)connecting to an end of the main gas pipe (43) and the gas passages(57,58) on the outdoor unit's (2A,2B) side. The main gas pipe (43) isconnected at the other end thereof to the indoor gas pipes (35) of theindoor units (3A,3B).

The piping unit (11) is so composed that the liquid passages (53,54) ofthe liquid lines (5LA,5LB) on the outdoor unit's (2A,2B) side, the mainliquid passage (42) of the main liquid line (4L), the gas passages(57,58) of the gas lines (5GA,5GB) on the outdoor unit's (2A,2B) side,and the main gas passage (44) of the main gas line (4G) are integrallyformed and unitized.

Further, as a feature of the present invention, the piping unit (11) hasa liquid stop valve (V1) and a gas stop valve (V2) which are integrallyunitized. The gas stop valve (V2) is disposed in the gas passage (58) ofthe gas line (5GB) on the slave outdoor unit's (2B) side, and serves asa gas-line closing mechanism for opening and closing the gas passage(58). The gas stop valve (V2) is disposed in the proximity of aconnecting part between the gas passage (58) on the slave outdoor unit's(2B) side and the main gas passage (44) of the main gas line (4G), andcomposed so as to be fully closed based on a control signal from thecontroller (6) when the slave outdoor unit (2B) is deactivated duringheating operation.

The liquid stop valve (V1) is disposed in the liquid passage (54) of theliquid line (5LB) on the slave outdoor unit's (2B) side, and serves as aliquid-line closing mechanism for opening and closing the liquid passage(54). The liquid stop valve (V1) is disposed in the proximity of aconnecting part between the liquid passage (54) on the slave outdoorunit's (2B) side and the main liquid passage (42) of the main liquidline (4L), and composed so as to be fully closed based on a controlsignal from the controller (6) when the slave outdoor unit (2B) isdeactivated during cooling operation and heating operation.

As a feature of the present invention, the slave outdoor unit (2B) has abypass line (29) which is connected to the discharge and inlet sides ofthe compressor (21) so as to bypass the compressor (21). On the bypassline (29), there is provided a bidirectional bypass stop valve (V3) foropening and closing the bypass line (29). The bypass stop valve (V3)serves as a bypass closing mechanism. In the controller (6), there isprovided a refrigerant ejecting means (61), which opens, for a set time,e.g., for a few minutes, the bypass stop valve (V3), the outdoormotor-operated expansion valve (25), the liquid stop valve (V1) and thegas stop valve (V2) just after the slave outdoor unit (2B) isdeactivated during heating operation, thereby ejecting a liquidrefrigerant in the slave outdoor unit (2B) toward the master outdoorunit (2A).

Further, as a feature of the present invention, the controller (6) has arefrigerant-amount detecting means (62) and a refrigerant recoveringmeans (63). The refrigerant-amount detecting means (62) is composed soas to detect lack of a circulation amount of refrigerant, when the airconditioner (1) is in a heating operation and the slave outdoor unit(2B) is deactivated, in case that the outdoor motor-operated expansionvalve (25) of the master outdoor unit (2A) is fully opened and that asuperheating degree of a refrigerant of the outdoor heat exchanger (24)according to the detection signals of the outdoor-liquid temperaturesensor (Th3) and the inlet-gas temperature sensor (Th2) excesses a settemperature.

The refrigerant recovering means (63) is composed, in case that therefrigerant-amount detecting means (62) detects lack of a circulationamount of refrigerant when the slave outdoor unit (2B) is deactivatedduring heating operation, so as to open the liquid stop valve (V1) for aset time and throttle the indoor motor-operated expansion valve (33) fora set time, thereby reducing a pressure of a liquid refrigerant to asaturation pressure according to an open-air temperature. Thus, theliquid refrigerant in the slave outdoor unit (2B) in deactivation isevaporated and returned to the master outdoor unit (2A). In this case,the refrigerant recovering means (63) is composed, if the outdoormotor-operated expansion valve (25) of the slave outdoor unit (2B) indeactivation is not opened, so as to open the outdoor motor-operatedexpansion valve (25) for a set time.

Operation of Example 1

Description is made next about operations for controlling the airconditioner (1).

At a cooling operation, the four-way selector valve (22) is switched asshown in dash lines in FIG. 1. The respective high-pressure gasrefrigerants discharged from the compressors (21) of both the outdoorunits (2A,2B) are first condensed at the outdoor heat exchangers (24) toturn liquid refrigerants. The two flows of the liquid refrigerants meetat the main liquid passage (42) of the piping unit (11). Then, thecollected liquid refrigerant flows into the indoor units (3A,3B). Ineach of the indoor units (3A,3B), the liquid refrigerant is reduced inpressure at the indoor motor-operated expansion valve (33) andevaporated at the indoor heat exchanger (32) to turn a low-pressure gasrefrigerant. The gas refrigerant is distributed at the piping unit (11)to the gas passages (57,58) and then returned to the compressors (21) ofthe outdoor units (2A,2B). The cooling operation is made by repeatingthe above circulating process.

At a heating operation, the four-way selector valve (22) is switched asshown in solid lines in FIG. 1. The respective high-pressure gasrefrigerants discharged from the compressors (21) of both the outdoorunits (2A,2B) flow into the piping unit (11) and meet at the main gaspassage (44) of the piping unit (11). Then, the collected gasrefrigerant flows into the indoor units (3A,3B). The gas refrigerant iscondensed at each of the indoor heat exchangers (32) to turn a liquidrefrigerant. The liquid refrigerant flows through the main liquidpassage (42) of the piping unit (11) and then is distributed at thepiping unit (11) to the liquid passage (53,54) running to the outdoorunits (2A,2B). In the outdoor units (2A,2B), the distributed liquidrefrigerants are each reduced in pressure at the outdoor motor-operatedexpansion valve (25) and evaporated at the outdoor heat exchanger (24)to turn a low-pressure gas refrigerant. Then, the gas refrigerants arereturned to the compressors (21) of the outdoor units (2A,2B). Theheating operation is made by repeating the above circulating process.

In the above cooling and heating operations, the controller (6) controlsopenings of respective indoor motor-operated expansion valves (33) andopenings of respective outdoor motor-operated expansion valves (25) andcontrols the capacities of the compressors (21) of respective outdoorunits (2A,2B) in accordance with an indoor load. In detail, thecontroller (6) controls the capacity of the compressor (21) of the slaveoutdoor unit (2B) so as to be switched among 100%, 50%, and 0%, andcontrols the capacity of the compressor (21) of the master outdoor unit(2A) so as to be changed approximately in a linear proportion to anindoor load by the inverter circuit. When the load of the indoor units(3A,3B) is decreased so as to be responded by the capacity of the masteroutdoor unit (2A), the controller (6) deactivates the slave outdoor unit(2B).

Further, when the slave outdoor unit (2B) is deactivated during coolingoperation and heating operation, the controller (6) closes the liquidstop valve (V1) thereby preventing storage of the liquid refrigerantinto the receiver (27) and the like. In detail, because the pressure ofthe liquid refrigerant at the operation time is higher than a saturationpressures according to an open-air temperature, the liquid refrigerantmay be stored in the receiver (27). The controller (6) prevents thestorage of the liquid refrigerant.

In addition, when the slave outdoor unit (2B) is deactivated duringheating operation, the controller (6) closes the gas stop valve (V2),thereby preventing storage of the liquid refrigerant into the slaveoutdoor unit (2B) in deactivation and preventing lack of a circulationamount of refrigerant between the master outdoor unit (2A) and theindoor units (3A,3B).

Just after the slave outdoor unit (2B) is deactivated during heatingoperation, the refrigerant ejecting means (61) opens the bypass stopvalve (V3), the outdoor motor-operated expansion valve (25) of the slaveoutdoor unit (2B), the liquid stop valve (V1) and the gas top valve (V2)for a set time, e.g., for a few minutes. As a result of this, thehigh-pressure gas refrigerant flows from the master outdoor unit (2A)into the liquid line (5LB) via the gas line (5GB) of the slave outdoorunit (2B), so that the liquid refrigerant in the slave outdoor unit (2B)in deactivation is ejected into the main liquid line (41) or the like.Accordingly, lack of the a circulation amount of refrigerant isprevented.

In detail, when the refrigerant flows through the main gas line (4G) orthe like, the pressure of the refrigerant is reduced due to a pressureloss. In the indoor units (3A,3B) at a heating operation, the differencebetween the pressure losses of the indoor units (3A,3B) resulting fromthe difference between the piping lengths thereof is compensated by theindoor motor-operated expansion valve (33). As a result of this, thepressure of the refrigerant in the main liquid line (4L) becomes lowerthan the pressure of the refrigerant discharged from the compressor(21), so that the liquid refrigerant in the slave outdoor unit (2B) isejected into the main liquid line (4L) or the like.

When the air conditioner (1) is in heating operation and while the slaveoutdoor unit (2B) is deactivated, the refrigerant-amount detecting means(62) detects whether a circulation amount of refrigerant is lacking ornot. In case that the outdoor motor-operated expansion valve (25) of themaster outdoor unit (2A) is fully opened and that the superheatingdegree of the refrigerant of the outdoor heat exchanger (24) accordingto the detection signals of the outdoor-liquid temperature sensor (Th3)and the inlet-gas temperature sensor (Th2) excesses a set temperature,the refrigerant-amount detecting means (62) detects lack of acirculation amount of refrigerant.

When the refrigerant-amount detecting means (62) detects the lack of acirculating amount of refrigerant, the refrigerant recovering means (63)opens the liquid stop valve (V1) for a set time and throttles the indoormotor-operated expansion valve (33) for a set time to reduce thepressure of liquid the refrigerant to a saturation pressure according toan open-air temperature, so that the liquid refrigerant in the slaveoutdoor unit (2B) in deactivation is evaporated and thus the evaporatedrefrigerant is returned to the master outdoor unit (2A). In this case,if the outdoor motor-operated expansion valve (25) of the slave outdoorunit (2B) in deactivation is not opened, the refrigerant recoveringmeans (63) opens the outdoor motor-operated expansion valve (25) for aset time.

Effects of Example 1

According to this example, since the gas stop valve (V2) is provided onthe gas line (5GB) connecting to the slave outdoor unit (2B), the gasstop valve (V2) can be closed when the slave outdoor unit (2B) isdeactivated during heating operation, thereby preventing a liquidrefrigerant from storing in the slave outdoor unit (2B) in deactivation.This prevents lack of a circulation amount of refrigerant between themaster outdoor unit (2A) and the indoor units (3A,3B).

Further, since the liquid stop valve (V1) is provided on the liquid line(5LB) connecting to the slave outdoor unit (2B), the liquid stop valve(V1) can be closed when the slave outdoor unit (2B) is deactivatedduring cooling operation and heating operation, thereby preventing aliquid refrigerant from being stored in the receiver (27) and the like.

As a result of this, a plurality of outdoor units (2A,2B) can becombined. In addition, since a plurality of outdoor units (2A,2B) havingdifferent capacities from each other can be produced and combined, thisenables a few kinds of outdoor units (2A,2B) to cope with a plurality ofindoor units (3A,3B).

Just after the slave door unit (2B) is deactivated during heatingoperation, the refrigerant ejecting means (61) operates so that thehigh-pressure gas refrigerant flows into the liquid line (5LB) throughthe slave outdoor unit (2B). Accordingly, the liquid refrigerant in theslave outdoor unit (2B) in deactivation is ejected into the main liquidline (41) or the like, thereby securely preventing lack of circulationamount of refrigerant.

When the refrigerant-amount detecting means (62) detects lack of acirculation amount of refrigerant, the refrigerant recovering means (63)throttles the indoor motor-operated expansion valve (33) to reduce thepressure of the liquid refrigerant to a saturation pressure according toan open-air temperature. As a result of this, the liquid refrigerant inthe slave outdoor unit (2B) which is deactivated during heatingoperation is evaporated and returned to the master outdoor unit (2A).Accordingly, lack of a circulation amount of refrigerant can be securelyprevented at any time.

Further, since piping connections between the outdoor units (2A,2B) andthe indoor units (3A,3B) are formed into the single piping unit (11), anangle of tilt required for backing oil can be secured and a part ofpiping to be horizontally arranged can be securely held in a horizontalposition. Accordingly, oil backing can be secured and a flash of liquidrefrigerant can be prevented. This enables high-reliable airconditioning. In addition, since the number of pipes can be reduced whentwo outdoor units (2A,2B) are installed, this reduces the number ofsteps at a pipe arrangement, thereby simplifying the pipe arrangement.

EXAMPLE 2

FIG. 2 shows another example of a refrigeration apparatus of the presentinvention. A single receiver (12) is provided in the piping unit (11).The receiver (12) is disposed at a connecting part between the mainliquid passage (42) and the liquid passages (53,54) running to theoutdoor units (2A,2B). The receiver (12) stores a liquid refrigerant,collects a liquid refrigerant from the outdoor units (2A,2B) to the mainliquid line (4L) during cooling operation, and distributes a liquidrefrigerant from the main liquid line (4L) to the outdoor units (2A,2B)during heating operation. In this example, the receivers (27) as shownin FIG. 1 are dispensed with, and the liquid stop valve (V1) is alsodispensed with because the outdoor motor-operated expansion valve (25)is fully closed instead of the closure of the liquid stop valve (V1).

In this example, the controller (6) serves as a full-closure controlmeans for fully closing the outdoor motor-operated expansion valve (25)of the slave outdoor unit (2B) when the slave outdoor unit (2B) isdeactivated during refrigerating operation.

According to this example, since provision of the single receiver (12)can dispense with respective receivers in the outdoor units (2A,2B),this reduces the number of elements. Further, since distribution of aliquid refrigerant is securely carried out, an unbalanced flow ofrefrigerant can be securely prevented even when a flash of gas flowsinto the main liquid line (4L) or the like. Other constructions,operations and effects are the same as in Example 1 shown in FIG. 1.

Modification 1 of Example 2

FIG. 3 is a valve circuit (13) showing a modification of the above gasstop valve (V2). The valve circuit (13) is composed of a first passage(13a) having a non-return valve (V4) through which a gas refrigerantflows from the slave outdoor unit (2B) into the main gas line (4G), anda second passage (13b) having a stop valve (V5) which opens at a coolingoperation.

Modification 2 of Example 2

FIG. 4 is an external-equalizing-type reversible valve (7) showinganother modification of the gas stop valve (V2). Theexternal-equalizing-type reversible valve (7) is connected to a pilotcircuit (14). The pilot circuit (14) is composed of: a high-pressurecircuit (14a) which is connected to the main gas line (4G) and the mainliquid line (4L), has non-return valves (V6,V7) and conducts ahigh-pressure refrigerant; and a low-pressure circuit (14b) which isconnected to the main gas line (4G) and the main liquid line (4L), hasnon-return valves (V8,V9) and holds a low pressure state.

As shown in FIG. 5 and FIG. 6, the external-equalizing-type reversiblevalve (7) has a valve base (71) and a pilot valve (72). The valve base(71) is composed of a casing (73), a spool (74) reciprocatably disposedin the casing (73) and pressure rooms (75a,75b) formed on both sides ofthe spool (74) in the casing (73). The valve base (71) is connected tothe gas passage (58) on the slave outdoor unit's (2B) side and connectedto two pilot pipes (76a,76b) through which the pressure rooms (75a,75b)are communicated with each other. The gas passage (58) is switchedbetween a communicating state (see FIG. 5) and a closing state (see FIG.6) by the movement of the spool (74).

The pilot valve (72) is composed of a casing (77) and a plunger (78)reciprocally disposed in the casing (77). In the pilot valve (72), thetwo pilot pipes (76a,76b) are connected to the high-pressure circuit(14a) and the low-pressure circuit (14b). The plunger (78) is moved bythe control signals of the controller (6), so that the high-pressure gasor the low-pressure gas is led to the pressure rooms (75a,75b) therebymoving the spool (74). According to the movement of the spool (74), thegas passage (58) is communicated or shut off.

EXAMPLE 3

FIG. 7 shows another example of a refrigeration apparatus of the presentinvention. In this example, a refrigerant recovering line (8) isprovided in addition to the air conditioner (1) shown in FIG. 1.

The refrigerant recovering line (8) is composed of a refrigerantrecovering pipe (81) extending outward from the master outdoor unit(2A), and a refrigerant recovering passage (82) connected to an outerend of the refrigerant recovering pipe (81). An inner end of therefrigerant recovering pipe (81) is connected to the gas-refrigerantpipe (26) disposed between the outdoor heat exchanger (24) and thefour-way selector valve (22) of the master outdoor unit (2A).

The refrigerant recovering passage (82) is connected at an outer endthereof to the gas passage (58) on the slave outdoor unit's (2B) sideand has a capillary (73) and a non-return valve (V10) for allowing arefrigerant to flow from the gas passage (58) to the master outdoor unit(2A). Further, in the refrigerant recovering line (8), the refrigerantrecovering passage (82), the capillary (83), and the non-return valve(V10) are unitized with the piping unit (11) so as to be incorporatedthereinto.

Thus, since the refrigerant recovering line (8) is incorporated into thepiping of the air conditioner (1), when the slave outdoor unit (2B) isdeactivated during heating operation, the refrigerant recovering line(8) establishes communications between the gas passage (58) connectingto the slave outdoor unit (2B) and a low-pressure gas side of the masteroutdoor unit (2A). Accordingly, a liquid refrigerant can be preventedfrom being stored into the slave outdoor unit (2B). In addition, sincethe refrigerant ejecting means (61) and the refrigerant recovering means(63) as in the example shown in FIG. 1 can be dispensed with, theconstruction of the air conditioner (1) can be simplified. Otherconstructions, operations, and effects are the same as in Example 1shown in FIG. 1.

Modification of Example 3

FIG. 8 shows a modification of Example 3 shown in FIG. 7. A singlereceiver (12) is provided in the piping unit (11). The receiver (12) isdisposed at a connecting part between the main liquid passage (42) andthe liquid passages (53,54) running to the outdoor units (2A,2B). Thereceiver (12) stores a liquid refrigerant, collects a liquid refrigerantfrom the outdoor units (2A,2B) to the main liquid line (4L) duringcooling operation, and distributes a liquid refrigerant from the mainliquid line (4L) to the outdoor units (2A,2B) during heating operation.In this example, the receivers (27) as shown in FIG. 7 are dispensedwith, and the liquid stop valve (V1) is also dispensed with because theoutdoor motor-operated expansion valve (25) is fully closed instead ofthe closure of the liquid stop valve (V1).

EXAMPLE 4

FIG. 9 shows still another example of the air conditioner (1), that is,an example of refrigeration apparatus of the present invention. Thisexample is so composed that a branch line (5a) and a constant-pressurecircuit (9) are provided in the air conditioner (1) shown in FIG. 1. Thebranch line (5a) is composed of a branch pipe (5b) extending outwardfrom the master outdoor unit (2A), and a branch passage (5c) connectedto an outer end of the branch pipe (5b). An inner end of the branch pipe(5b) is connected to the gas-refrigerant pipe (26) disposed between theoutdoor heat exchanger (24) and the four-way selector valve (22) of themaster outdoor unit (2A). An outer end of the branch passage (5c) isconnected to the constant-pressure circuit (9).

The constant-pressure circuit (9) has a normally high-pressure passage(91) and a normally low-pressure passage (92). One end of the normallyhigh-pressure passage (91) and one end of the normally low-pressurepassage (92) are connected to the branch passage (5c) via non-returnvalves (V11,V12) respectively, and respective other ends of the normallyhigh-pressure passage (91) and the normally low-pressure passage (92)are connected to the main gas passage (44) of the main gas line (4G) viaa four-way selector valve (V13). The non-return valve (V11) of thenormally high-pressure passage (91) is composed so as to allow arefrigerant to flow from the branch passage (5c) to the normallyhigh-pressure passage (91), and the non-return valve (V12) of thenormally low-pressure passage (92) is composed so as to allow arefrigerant to flow from the normally low-pressure passage (92) to thebranch passage (5c). The four-way selector valve (V13) is switched asshown in dash lines at a cooling operation to conduct a low-pressure gasrefrigerant into the normally low-pressure passage (92), and switched asshown in solid lines at a heating operation to conduct a high-pressuregas refrigerant into the normally high-pressure passage (91). Thenormally high-pressure passage (91) is connected to the main gas passage(44) and the gas passage (58) running to the slave outdoor unit (2B)through non-return valves (V14,V15) for allowing a refrigerant to flowinto the normally high-pressure passage (91), so that the normallyhigh-pressure passage (91) is held in a high-pressure state at any time.The normally low-pressure passage (92) is connected to the main gaspassage (44) and the gas passage (58) running to the slave outdoor unit(2B) through non-return valves (V16,V17) for allowing a refrigerant toflow into the main gas passage (44) and the gas passage (58), so thatthe normally low-pressure passage (92) is held in a low-pressure stateat any time.

A refrigerant recovering passage (8a) is connected between the normallylow-pressure passage (92) and the gas passage (58) running to the slaveoutdoor unit (2B). In the refrigerant recovering passage (8a), acapillary (84) and a stop valve (V18) are provided. The stop valve (V18)is composed so as to open when the slave outdoor unit (2B) isdeactivated during heating operation.

The constant-pressure circuit (9), the branch passage (5c), therefrigerant recovering passage (8a), the capillary (84), and the stopvalve (V18) are unitized with the piping unit (11) so as to beincorporated thereinto.

In this example, since the gas passage (57) running to the masteroutdoor unit (2A) is directly connected to the main gas passage (44),the gas stop valve (V2) as shown in FIG. 1 is dispensed with.

According to this example, since the constant-pressure circuit (9) andthe refrigerant recovering passage (8a) is incorporated into the pipingof the air conditioner (1), when the slave outdoor unit (2B) isdeactivated during heating operation, the normally low-pressure passage(92) and the refrigerant recovering passage (8a) establishcommunications between the gas passage (58) running to the slave outdoorunit (2B) and a low-pressure gas side of the master outdoor unit (2A).Accordingly, a liquid refrigerant is prevented from being stored intothe slave outdoor unit (2B). Further, since the gas stop valve (V2) asshown in FIG. 7 is dispensed with, the number of elements can bereduced.

In addition, since the refrigerant ejecting means (61) and therefrigerant recovering means (63) as shown in the example of FIG. 1 canbe dispensed with, the construction of the refrigeration apparatus canbe simplified. Other constructions, operations, and effects are the sameas in example shown in FIG. 1.

In this example, since the stop valve (V18) is closed during heatingoperation of the slave outdoor unit (2B), operation performance inheating is improved as compared with the case that the non-return valve(V10) as in Example 3 is used. However, the stop valve (V18) may bedispensed with, though the operation performance in heating is slightlylowered.

Modification of Example 4

FIG. 10 shows a modification of Example 4 shown in FIG. 9. A singlereceiver (12) is provided in the piping unit (11). The receiver (12) isdisposed at a connecting part between the main liquid passage (42) andthe liquid passages (53,54) running to the outdoor units (2A,2B). Thereceiver (12) stores a liquid refrigerant, collects a liquid refrigerantfrom the outdoor units (2A,2B) to the main liquid line (4L) duringcooling operation, and distributes a liquid refrigerant from the mainliquid line (4L) to the outdoor units (2A,2B) during heating operation.In this example, the receivers (27) as shown in FIG. 9 are dispensedwith, and the liquid stop valve (V1) is also dispensed with because theoutdoor motor-operated expansion valve (25) is fully closed instead ofthe closure of the liquid stop valve (V1).

EXAMPLE 5

FIG. 11 shows still another example of the air conditioner (1), that is,an example of the refrigeration apparatus of the present invention. Thisexample is so composed that a connecting as line (10) is provided in theair conditioner (1) shown in FIG. 2.

The connecting gas line (10) is connected at an end thereof to thegas-refrigerant pipe (26) extending from the outdoor heat exchanger (24)of the master outdoor unit (2A) and connected at the other end to thegas-refrigerant pipe (26) extending from the outdoor heat exchanger (24)of the slave master outdoor unit (2B). The connecting as line (10) iscomposed of connecting gas pipes (10a) extending outward from therespective outdoor units (2A,2B), a connecting gas passage (10b)connected at both ends thereof to respective outer ends of theconnecting gas pipes (10a), and a stop valve (V19) disposed in theconnecting gas passage (10b). The stop valve (V19) is a closingmechanism for fully closing, when the slave outdoor unit (2B) isdeactivated during cooling operation, to prevent a refrigerant fromflowing into the slave outdoor unit (2B).

The connecting gas passage (10b) and the stop valve (V19) are unitizedwith the piping unit (11) so as to be incorporated thereinto.

In either of cooling and heating operations, the stop valve (V19) isopened in the running of both the outdoor units (2A,2B). Thus, ahigh-pressure gas refrigerant flows through both the outdoor heatexchangers (24) uniformly during cooling operation and a low-pressuregas refrigerant flows through both the outdoor heat exchangers (24)uniformly during heating operation.

For example, when an operating capacity of the slave outdoor unit (2B)is large with respect to a load thereof, a part of the refrigerantdischarged from the compressor (21) of the slave outdoor unit (2B) flowsinto the outdoor heat exchanger (24) of the master outdoor unit (2A) viathe connecting gas line (10).

When the slave outdoor unit (2B) is deactivated during coolingoperation, the stop valve (V19) is fully closed and the gas stop valve(V2) is opened, so that the refrigerant in the slave outdoor unit (2B)is sucked into a low-pressure side of the master outdoor unit (2A). Whenthe slave outdoor unit (2B) is deactivated during heating operation, thestop valve (V19) is opened and the gas stop valve (V2) is fully closed,so that the refrigerant in the slave outdoor unit (2B) is sucked into alow-pressure side of the master outdoor unit (2A) via the connecting gasline (10).

According to this example, since the gas-refrigerant pipe (26) of theoutdoor heat exchanger (24) of the master outdoor unit (2A) iscommunicated with the gas-refrigerant pipe (26) of the outdoor heatexchanger (24) of the slave outdoor unit (2B), circulation amounts ofrefrigerants which flow through the respective outdoor heat exchangers(24) can be approximately equal to each other, thereby increasing acoefficient of performance (COP) of the refrigeration apparatus. Inaddition, between the outdoor units (2A,2B), a high-pressure sensor fordetecting a high pressure at a cooling operation and a low-pressuresensor for detecting a low pressure at a heating operation can beshared. This reduces the number of elements. Further, when the slaveoutdoor unit (2B) is deactivated during heating operation, therefrigerant in the slave thermal source unit (2B) in deactivation can besecurely returned to the master outdoor unit (2A). Other constructions,operations, and effects are the same as Example 2 shown in FIG. 2.

Modification of Example 5

FIG. 12 shows a modification of the above Example 5. In this example, anauxiliary bypass line (29a) is arranged in parallel with the bypass line(29).

On the auxiliary bypass line (29a), a non-return valve (V20) is providedfor allowing a refrigerant to flow from the inlet side to the dischargeside of the compressor (21).

When the slave outdoor unit (2B) is deactivated during heatingoperation, the refrigerant in the slave outdoor unit (2B) is sucked intoa low-pressure side of the master outdoor unit (2A) via the connectinggas line (10), as explained in the above Example 5. At this time, thefour-way selector valve (22) may be in a state of a cooling operation asshown in solid lines in FIG. 12. In such a case, when the bypass stopvalve (V3) of the bypass line (29) is a one-way valve for allowing arefrigerant to flow from the discharge side to the inlet side of thecompressor (21), the refrigerant shows through compressor (21).Therefore, the auxiliary bypass line (29a) is provided in the slaveoutdoor units (2B) to securely suck the refrigerant into the masteroutdoor unit (2A).

Other Modifications

Each of the air conditioners (1) of the above examples is composed oftwo outdoor units (2A,2B) and two indoor units (3A,3B). The airconditioner of the present invention may be composed of three or moreoutdoor units and three or more indoor units. In such a case, one of theplural outdoor units serves as a master outdoor unit.

In the example of FIG. 1, the receiver (12) may be disposed at aconnecting part between the main liquid passage (42) and the liquidpassages (53,54) extending toward the outdoor units (2A,2B), as shown inFIG. 2. According to this, storage of a refrigerant in case of the airconditioner having long piping length is prevented. In the example ofFIG. 1, the refrigerant-amount detecting means (62) is composed so as todetect lack of a circulation amount of refrigerant based on the openingof the outdoor motor-operated expansion valve (25) and superheatingdegree. However, the refrigerant-amount detecting means (62) may becomposed so as to detect lack of a circulation amount of refrigerantwhen an evaporation temperature of a refrigerant in the outdoor heatexchanger (24) is lower by a set degree than an open-air temperature.

In the example of FIG. 1, the refrigerant recovering means (63) iscomposed so as to recover a refrigerant for a set time. However, apressure sensor is disposed on the compressor's (21) side of the outdoorheat exchanger (24) or the like in the slave outdoor unit (2B), and therefrigerant recovering means (63) may be composed so as to finish therecover of the refrigerant when the pressure sensor detects that thepressure of the refrigerant is decreased to a set pressure.

In the examples of FIG. 2, FIG. 3, FIG. 4, FIG. 8, and FIG. 10, theliquid stop valve (V1) is dispensed with, for the reason that theoutdoor motor-operated expansion valve (25) can be freely opened andclosed. However, in case of using a valve which cannot be freely openedand closed such as an automatic expansion valve, the liquid stop valve(V1) is provided for preventing storage of a refrigerant, as shown inFIG. 1 and the like.

In the examples of FIG. 1 and the like, the bidirectional bypass stopvalve (V3) is provided. However, as shown in FIG. 12, a one-way bypassstop valve (V3) and an auxiliary bypass line (29a) may be provided.

In the above examples, description is made about an air conditionerwhich is operated reversibly between cooling and heating cycles. The airconditioner may be an air conditioner only for cooling. In such a case,the four-way selector valve (22) and the outdoor motor-operatedexpansion valve (25) each shown in FIG. 1 and the gas stop valve (V2)are dispensed with. When the slave outdoor unit (2B) is deactivatedduring cooling operation, the liquid stop valve (V1) is fully closed.

Further, in the air conditioner only for cooling, as shown in FIG. 2,the receiver (12) may be disposed at a connecting part between the mainliquid passage (42) and the liquid passages (53,54) extending toward theoutdoor units (2A,2B).

Industrial Applicability

As described above, according to the refrigeration apparatus of thepresent invention, a plurality of outdoor units can be provided andeffective cooling and heating operations can be made by using theoutdoor units. Accordingly, the refrigeration apparatus of the presentinvention is suitable for air conditioning for a large building or thelike.

I claim:
 1. A refrigeration apparatus, comprising:liquid lines, gaslines, a main liquid line, a main gas line; a main thermal source unitand a slave thermal source unit each having a compressor, athermal-source-side heat exchanger connected at one end thereof toexchangeably a discharge side and an inlet side of the compressor and atthe other end thereof to the corresponding liquid line and athermal-source-side heat expansion mechanism which is disposed on thecorresponding liquid line and is capable of regulating an openingthereof, each compressor being exchangeably connected at the dischargeside and the inlet side thereof to the corresponding gas line; aconnecting circuit part for connecting respective outer ends of theliquid lines and of the gas lines to the main liquid line and the maingas line respectively so that the thermal source units are arranged inparallel with each other; a plurality of user units having a user-sideheat exchanger and being connected in parallel to the main liquid lineand the main gas line; a receiver for connecting liquid lines and themain liquid line; a gas-line closing mechanism provided at the gas lineon the side of the slave thermal source unit; and a controller forcontrolling the gas line closing mechanism of the slave thermal sourceunit to be fully closed when the slave thermal source unit halts itsheating operation under the condition that the main thermal source unitcontinues its operation, and for controlling the thermal-source-sideheat expansion mechanism of the slave thermal source unit to be fullyclosed when the slave thermal source unit halts its operations under thecondition that the main thermal source unit continues its operation. 2.The refrigeration apparatus according to claim 1, further comprising:abypass line (29) which bypasses the compressor (21) of the slave thermalsource unit (2B) and which is connected to the discharge and inlet sidesof the compressor (21); a bypass closing mechanism (V3) disposed on thebypass line (29); and refrigerant ejecting means (61) for ejecting aliquid refrigerant remaining in the slave thermal source unit (2B) insuch a manner as to open the bypass closing mechanism (V3) and thethermal-source-side expansion mechanism (25) each included in the slavethermal source unit (2B) in deactivation, and the gas-line closingmechanism (V2) for a set time just after the slave thermal source unit(2B) is deactivated during heating operation.
 3. The refrigerationapparatus according to claim 1 or 2, further comprising:a user-sideexpansion mechanism (33) which is disposed in each of the user units(3A, 3B) and located between the main liquid line (4L) and the user-sideheat exchanger (32); refrigerant-amount detecting means (62) fordetecting lack of a circulation amount of refrigerant; and refrigerantrecovering means (63) for recovering a refrigerant from the slavethermal source unit (2B) in deactivation when the slave thermal sourceunit (2B) is deactivated during heating operation and therefrigerant-amount detecting means (62) detects the lack of acirculation amount of refrigerant, in such a manner as to open thethermal-source-side expansion mechanism (25) of the slave thermal sourceunit (2B) in deactivation and throttle the user-side expansion mechanism(33) so as to reduce a pressure of the liquid refrigerant to asaturation pressure according to an open-air temperature.
 4. Therefrigeration apparatus according to claim 1, whereina refrigerantrecovering line (8) through which a refrigerant flows from the slavethermal source unit (2B) to the master thermal source unit (2A) isconnected between a gas-refrigerant pipe (26) extending from thethermal-source-side heat exchanger (24) of the master thermal sourceunit (2A) and the gas line (5GB) extending from the slave thermal sourceunit (2B).
 5. The refrigeration apparatus according to claim 1, furthercomprising:a connecting gas line (10) which is connected at respectiveends thereof to the respective gas-refrigerant pipes (26) of thethermal-source-side heat exchangers (24) of the thermal source units(2A, 2B) and which has a closing mechanism (V19) for preventing arefrigerant from flowing, when at least one thermal source unit (2B) isdeactivated during cooling operation, into the thermal source unit (2B)in deactivation.
 6. The refrigeration apparatus according to any ofclaims 1, 4 and 5, whereinthe connecting circuit part (11) is formed ina single unit.
 7. The refrigeration apparatus according to claim 2,wherein the bypass line (29) comprises an auxiliary bypass line (29a)having a non-return valve which allows a refrigerant to flow from theinlet side to the discharge side to the compressor (21), the auxiliarybypass line (29a) being connected between the inlet side and thedischarge side of the compressor (21), bypassing the compressor (21). 8.A refrigeration apparatus, comprising:a master thermal source unithaving a compressor, a thermal-source-side heat exchanger connected atan end thereof to the discharge side and the inlet side of thecompressor so as to be switchable between the two sides of thecompressor and connected at the other end to a liquid line, and athermal-source-side expansion mechanism which is disposed on the liquidline and capable of regulating an opening thereof, in which a gas lineis connected to the discharge side and the inlet side of the compressorso as to be switchable between the two sides of the compressor; a slavethermal source unit having a compressor, a thermal-source-side heatexchanger connected at an end thereof to the discharge side and theinlet side of the compressor so as to be switchable between the twosides of the compressor and connected at the other end to a liquid line,and a thermal-source-side expansion mechanism which is disposed on theliquid line and capable of regulating an opening thereof, in which a gasline is connected to the discharge side and the inlet side of thecompressor so as to be switchable between the two sides of thecompressor; a connecting circuit part for connecting outer ends of theliquid lines and outer ends of the gas lines to a main liquid line and amain gas line respectively so that the thermal source units are arrangedin parallel with each other; a plurality of user units which each have auser-side heat exchanger and which are connected to the main liquid lineand the main gas line so as to be arranged in parallel with one another;a receiver which is disposed at a connecting part located between theliquid lines and the main liquid line and connects each of the liquidlines to the main liquid line; a gas-line closing mechanism which isdisposed on the gas line extending toward the slave thermal source unitand fully closed when the slave thermal source unit is deactivatedduring heating operation; full-closure control means for controlling thethermal-source-side expansion mechanism of the slave thermal source unitin deactivation to be fully closed when the slave thermal source unit isdeactivated during refrigerating operation; a bypass line which bypassesthe compressor of the slave thermal source unit and which is connectedto the discharge and inlet sides of the compressor; a bypass lineclosing mechanism disposed on the bypass line; and refrigerant ejectingmeans for ejecting a liquid refrigerant remaining in the slave thermalsource unit in such a manner as to open the bypass closing mechanism andthe thermal-source-side expansion mechanism each included in the slavethermal source unit in deactivation, and the gas-line closing mechanismfor a set time just after the slave thermal source unit is deactivatedduring heating operation.
 9. The refrigeration apparatus according toclaim 8, further comprising:a user-side expansion mechanism which isdisposed in each of the user units and located between the main liquidline and the user-side heat exchanger; refrigerant-amount detectingmeans for detecting lack of a circulation amount of refrigerant; andrefrigerant recovering means for recovering a refrigerant from the slavethermal source unit in deactivation when the slave thermal source unitis deactivated during heating operation and the refrigerant-amountdetecting means detects the lack of a circulation amount of refrigerant,in such a manner as to open the thermal-source-side expansion mechanismof the slave thermal source unit in deactivation and throttle theuser-side expansion mechanism of the slave thermal source unit indeactivation and throttle the user-side expansion mechanism so as toreduce a pressure of the liquid refrigerant to a saturation pressureaccording to an open-air temperature.
 10. The refrigeration apparatusaccording to claim 8, wherein the bypass line comprises an auxiliarybypass line having a non-return valve which allows a refrigerant to flowfrom the inlet side to the discharge side to the compressor, theauxiliary bypass line being connected between the inlet side and thedischarge side of the compressor, bypassing the compressor.
 11. Arefrigeration apparatus, comprising:a master thermal source unit havinga compressor, a thermal-source-side heat exchanger connected at an endthereof to the discharge side and the inlet side of the compressor so asto be switchable between the two sides of the compressor and connectedat the other end to a liquid line, and a thermal-source-side expansionmechanism which is disposed on the liquid line and capable of regulatingan opening thereof, in which a gas line is connected to the dischargeside and the inlet side of the compressor so as to be switchable betweenthe two sides of the compressor; a slave thermal source unit having acompressor, a thermal-source-side heat exchanger connected at an endthereof to the discharge side and the inlet side of the compressor so asto be switchable between the two sides of the compressor and connectedat the other end to a liquid line, and a thermal-source-side expansionmechanism which is disposed on the liquid line and capable of regulatingan opening thereof, in which a gas line is connected to the dischargeside and the inlet side of the compressor so as to be switchable betweenthe two sides of the compressor; a connecting circuit part forconnecting outer ends of the liquid lines and outer ends of the gaslines to a main liquid line and a main gas line respectively so that thethermal source units are arranged in parallel with each other; aplurality of user units which each have a user-side heat exchanger andwhich are connected to the main liquid line and the main gas line so asto be arranged in parallel with one another; a receiver which isdisposed at a connecting part located between the liquid lines and themain liquid line and connects each of the liquid lines to the mainliquid line; a gas-line closing mechanism which is disposed on the gasline extending toward the slave thermal source unit and fully closedwhen the slave thermal source unit is deactivated during heatingoperation; full-closure control means for controlling thethermal-source-side expansion mechanism of the slave thermal source unitin deactivation to be fully closed when the slave thermal source unit isdeactivated during refrigerating operation; a user-side expansionmechanism which is disposed in each of the user units and locatedbetween the main liquid line and the user-side heat exchanger;refrigerant-amount detecting means for detecting lack of a circulationamount of refrigerant; and refrigerant recovering means for recovering arefrigerant from the slave thermal source unit in deactivation when theslave thermal source unit is deactivated during heating operation andthe refrigerant-amount detecting means detects the lack of a circulationamount of refrigerant, in such a manner as to open thethermal-source-side expansion mechanism of the slave thermal source unitin deactivation and throttle the user-side expansion mechanism of theslave thermal source unit in deactivation and throttle the user-sideexpansion mechanism so as to reduce a pressure of the liquid refrigerantto a saturation pressure according to an open-air temperature.
 12. Arefrigeration apparatus, comprising:a master thermal source unit havinga compressor, a thermal-source-side heat exchanger connected at an endthereof to the discharge side and the inlet side of the compressor so asto be switchable between the two sides of the compressor and connectedat the other end to a liquid line, and a thermal-source-side expansionmechanism which is disposed on the liquid line and capable of regulatingan opening thereof, in which a gas line is connected to the dischargeside and the inlet side of the compressor so as to be switchable betweenthe two sides of the compressor; a slave thermal source unit having acompressor, a thermal-source-side heat exchanger connected at an endthereof to the discharge side and the inlet side of the compressor so asto be switchable between the two sides of the compressor and connectedat the other end to a liquid line, and a thermal-source-side expansionmechanism which is disposed on the liquid line and capable of regulatingan opening thereof, in which a gas line is connected to the dischargeside and the inlet side of the compressor so as to be switchable betweenthe two sides of the compressor; a connecting circuit part forconnecting outer ends of the liquid lines and outer ends of the gaslines to a main liquid line and a main gas line respectively so that thethermal source units are arranged in parallel with each other; aplurality of user units which each have a user-side heat exchanger andwhich are connected to the main liquid line and the main gas line so asto be arranged in parallel with one another; a receiver which isdisposed at a connecting part located between the liquid lines and themain liquid line and connects each of the liquid lines to the mainliquid line; a gas-line closing mechanism which is disposed on the gasline extending toward the slave thermal source unit and fully closedwhen the slave thermal source unit is deactivated during heatingoperation; and full-closure control means for controlling thethermal-source-side expansion mechanism of the slave thermal source unitin deactivation to be fully closed when the slave thermal source unit isdeactivated during refrigerating operation; wherein a refrigerantrecovering line through which a refrigerant flows from the slave thermalsource unit to the master thermal source unit is connected between agas-refrigerant pipe extending from the thermal-source-side heatexchanger of the master thermal source unit and the gas line extendingfrom the slave thermal source unit.
 13. The refrigeration apparatusaccording to claim 12, whereinthe connecting circuit part is formed in asingle unit.
 14. A refrigeration apparatus, comprising:a master thermalsource unit having a compressor, a thermal-source-side heat exchangerconnected at an end thereof to the discharge side and the inlet side ofthe compressor so as to be switchable between the two sides of thecompressor and connected at the other end to a liquid line, and athermal-source-side expansion mechanism which is disposed on the liquidline and capable of regulating an opening thereof, in which a gas lineis connected to the discharge side and the inlet side of the compressorso as to be switchable between the two sides of the compressor; a slavethermal source unit having a compressor, a thermal-source-side heatexchanger connected at an end thereof to the discharge side and theinlet side of the compressor so as to be switchable between the twosides of the compressor and connected at the other end to a liquid line,and a thermal-source-side expansion mechanism which is disposed on theliquid line and capable of regulating an opening thereof, in which a gasline is connected to the discharge side and the inlet side of thecompressor so as to be switchable between the two sides of thecompressor; a connecting circuit part for connecting outer ends of theliquid lines and outer ends of the gas lines to a main liquid line and amain gas line respectively so that the thermal source units are arrangedin parallel with each other; a plurality of user units which each have auser-side heat exchanger and which are connected to the main liquid lineand the main gas line so as to be arranged in parallel with one another;a receiver which is disposed at a connecting part located between theliquid lines and the main liquid line and connects each of the liquidlines to the main liquid line; a gas-line closing mechanism which isdisposed on the gas line extending toward the slave thermal source unitand fully closed when the slave thermal source unit is deactivatedduring heating operation; full-closure control means for controlling thethermal-source-side expansion mechanism of the slave thermal source unitin deactivation to be fully closed when the slave thermal source unit isdeactivated during refrigerating operation; and a connecting gas linewhich is connected at respective ends thereof to the respectivegas-refrigerant pipes of the thermal-source-side heat exchangers of thethermal source units and which has a closing mechanism for preventing arefrigerant from flowing, when at least one thermal source unit isdeactivated during cooling operation, into the thermal source unit indeactivation.
 15. The refrigeration apparatus according to claim 14,whereinthe connecting circuit part is formed in a single unit.
 16. Arefrigeration apparatus, comprising:a master thermal source unit havinga compressor, a thermal-source-side heat exchanger connected at an endthereof to the discharge side and the inlet side of the compressor so asto be switchable between the two sides of the compressor and connectedat the other end to a liquid line, and a thermal-source-side expansionmechanism which is disposed on the liquid line and capable of regulatingan opening thereof, in which a gas line is connected to the dischargeside and the inlet side of the compressor so as to be switchable betweenthe two sides of the compressor; a slave thermal source unit having acompressor, a thermal-source-side heat exchanger connected at an endthereof to the discharge side and the inlet side of the compressor so asto be switchable between the two sides of the compressor and connectedat the other end to a liquid line, and a thermal-source-side expansionmechanism which is disposed on the liquid line and capable of regulatingan opening thereof, in which a gas line is connected to the dischargeside and the inlet side of the compressor so as to be switchable betweenthe two sides of the compressor; a connecting circuit part forconnecting outer ends of the liquid lines and outer ends of the gaslines to a main liquid line and a main gas line respectively so that thethermal source units are arranged in parallel with each other; aplurality of user units which each have a user-side heat exchanger andwhich are connected to the main liquid line and the main gas line so asto be arranged in parallel with one another; a receiver which isdisposed at a connecting part located between the liquid lines and themain liquid line and connects each of the liquid lines to the mainliquid line; a gas-line closing mechanism which is disposed on the gasline extending toward the slave thermal source unit and fully closedwhen the slave thermal source unit is deactivated during heatingoperation; and full-closure control means for controlling thethermal-source-side expansion mechanism of the slave thermal source unitin deactivation to be fully closed when the slave thermal source unit isdeactivated during refrigerating operation; wherein the connectingcircuit part is formed in a single unit.